Field of the Invention
The present invention relates to a camera and a camera accessory interchangeably attachable to the camera such as an interchangeable lens.
Description of the Related Art
Such camera accessories (each hereinafter simply referred to as “an accessory”) receive, in a state of being attached to a camera, supply of power from the camera and perform communication of commands, data or the like with the camera. In order to perform such supply of power and communication, an attachment portion (mount) of the camera and that of the accessory are provided with multiple electrical contacts (each hereinafter simply referred to as “a contact”) in which paired ones are brought into contact with each other to establish electrical connection. Moreover, as a method of the attachment (coupling) of the camera and the accessory, bayonet coupling is often used in which the mounts of the camera and accessory are relatively rotated to cause bayonet claws provided in the respective mounts to engage with each other.
In some of such cameras and accessories, a signal to be used by the camera for determination of type of the accessory attached thereto is input from the accessory to the camera, via a specific contact (hereinafter referred to as “an accessory type determining contact”) among the multiple contacts provided in each mount of the accessory and camera. The camera receiving the signal switches, according to the determined accessory type, for example, a voltage or a method to be used for communication between the camera and the accessory.
In each of a camera and an interchangeable lens disclosed in Japanese Patent Laid-Open No. 09-211645, an engaging claw provided in its bayonet mount and a power supplying contact provided inside the bayonet mount to supply power from the camera to the interchangeable lens are arranged so as to overlap each other in a radial direction of the bayonet mount. This arrangement prevents a portion around the power supplying contact in the interchangeable lens from being displaced due to external force acting on the interchangeable lens, and thereby avoids that the supply of power from the camera to the interchangeable lens is stopped due to connection failure between the power supplying contacts.
However, the bayonet mounts of the camera and interchangeable lens disclosed in Japanese Patent Laid-Open No. 09-211645 are not provided with the accessory type determining contacts.
Moreover, the connection failure between the accessory type determining contacts causes the camera to make an erroneous determination of the type of the accessory, which results in setting of an improper communication voltage by the camera for the attached interchangeable lens and thereby may cause an erroneous operation of the accessory.